Method of and arrangement for starting frequency-transforming installations



' VOL YAG-E Jan. 12 ,1-926- 1,569,132

M. @SNUS ET AL METHOD OF AND ARRANGEMENT FOR STARTING FREQUENCY TRANSFORMING INSTALLATIONS Filed Oct. 25. 1922 I Fig. 2 Fig. 5

l l l i l l l I l l PRIMARY CUR/TENT Fff/MAEY Cl/fiFEl/T MENDEL (Janos 8c LEO AfiARNOWEaK 83% 1115 aito'vwe/t & q a

raenaa ,la i2, tea,

MENDELQSNQS All! D LEO KASARNOWSKI, OF REEL IN, GERMANY, ASS-IGNGES 'JlG nature CQRPQRATIUN OF AMERICA, A CORPQRATION 6F DELAWARE, I

THGD 01 AND ARRANGEMENT FQR, QTAETING FREQUENCY-TRANSFQEMEQTG INSTALLATIOETS.

Application filed October 25, 1922. erial Ito. 5%,842.

To all whom it may concern: I

Be it lmown that we, hinnonn Genes and Leo KAsARNowsKI, citizens ofltussia, and residents of Hallesches Ufer 12/13, Berlin,

SW. 11 Germany, have invented new and I m The present invention provides a method and arrangement whereby upon the switching in of the installation, it may be actuatedv with certainty and without disturloances Our invention is illustrated in the accom- 25 panying drawing, in which: I

Fig. l is a diagram of a circuit arrangement embodying the invention,

Fig. 2 is a characteristic curve oi the frequency changer, wherein the ordinates represent voltage and the absc1ssee, primary current.

' Fig. 3 is a'curve showing the relation between the seltinductance ot the frequency charger, represented by ordinates, and the primary current, denoted by abscissee, and

Fig, i is a diagram ot a modified term of our invention.

As is well lmown in physics, the actuation of the installation is impeded first of all due to the form oi. the magnetic'characten istic of the saturated iron part of the installation. lln the following this will he exemplified by means of the frequency stepupcircuit arrangement shown in' Fig. 1. ln this figure 9 may he a high frequency synchronous generator having the usual direct current field and whose armature supplies current through terminals pp to an iron core cholre coil or tranformer a, the iron of which is saturated under normal current conditions. as are the terminals of the work circuit of higher frequency l and (i designate a self inductance and a capacity the circuit for the Elm.

provided it pose of tuning. L, is a variable inductance connected in parallel with the generator and provided for the purpose of reducing its load. lhe self inductance L and the capacity Q are so adjusted that during operation the resultant reactance of the circuit L C pp is capacitive, i. e. that the current iiowing through this circuit leads the voltage;

this current may be entirely or partially supplied hy the inductance L If 7' and 1 designate the reactance of the inductance L and of the apparatus a? respectively, and it p, is the capacitive reactance of the condenser C then the alcove stated condition means that go, must he greater than (r d-r and that the resulting capacitive reactance p:p (r-l-r must be approximately equal to the inductive reactance r, of the choke coil L, for the basic frequency of the generator 9 Under these conditions the current of desired strength is obtained in the installation. However, the inductive reactance r is not constant but is to a great extent dependent .on the current. Fig. 2 shows a typical curve of the voltage characteristic of the apparatus d. This curve shows the dependence oiits effective normal voltage E on its eiiective primary current 'l. The relation E This is equal to the tangent of the angle which is formed, e. g. tor the point P between the radius-vector UP and the abscissa. It will he seen that the reactance will first increase, will reach its maximum value at point P and will "then decrease. This relation between the reactance rd and current T is graphically illustrated in 3. The curve shown in this figure shows that the reactance ml is much greater in the case small currents than with strong currents. This may he explained lay the fact that in the case of wealr currenta, since the iron is not saturated during the whole cycle, the flux is varied to greater extent, and the self-induction coeiiicient la whichdetermines the value oi rd, is therefore large. @n the other hand, in of strong currents during the major part or the oscillation period the instantaneous current values are suificient to saturate the iron. As a result of this during the part of the oscillation period the changes reactance 113.

W gives for each current thevalue of the a Mil I The reason for this is that while the in-.

in the flux and therefore in the instantaneous values of the self induction coefficient are correspondingly small, and the mean value of the "self induction coeflicient per period is therefore also small.

circuit of the apparatus d, not even if L and C are tuned for normal operation.

stallation is without current or the current T is very small, the reactance rd will be very large-whereby the installation is en- I tirely detuned. Furthermore, the current T cannot swing itself up to the necessary value for the following reasons Let us assume that the current T reaches a small value corresponding to point P in the voltage curve of Fig. 2. It cannot'further increase by itself because in this sphere an increasing current causes an increase in the value of the reactance m. Therefore, the current cannot increaseitself even if the generator voltage is constant; This is furthermore prevented because an increase in the current will automatically. reduce the voltage of the generator. The reasons for this are as follows: i

The resulting reactance p (r +rd) which must be capacitive when the current is normal, that is, p (1 +rd), will be inductive when rd is large because then the subtrahend is greater than the minuend 1),. Therefore the generator must supply lagging currents in both of the parallel branches of the arrangement, which causes the field and voltage of thegenerator to be weakened. If the current T could increase by itself, then its wattless, i. e. in the present case, lagging, component would also increase because the inductive reactance rd is still increasing in this sphere. For this reason, the generator would supply wattless current which would lag still more, and the generator would be (lo-energized to an even greater extent. This proves that if the current is weak and therefore the apparatus (1 is not saturated, a state of permanence is reached, whereby thecurrent cannot swing itself from the stage of balance that it has reached to the necessary amplitude.

However,-should we succeed in developing the current "beyond the; point P of the greatest reactance i'rd (see Fig. 2), then it wouldfurther increase by itself until a new state of balance .isreached which correspondsto the desired value. This is so beeausein this sphere of saturation, rd 'decreases withincreasing current. The resulting jreactance p=p (r +rd) will finally be capacitive, thecurrent of the respective branch L,, (3,, pp will be leading and increasing the inductance L and the field and voltage of the generator will automatically increase causing in turn a further increase of the current T until the reactance rd will be sufficiently small so that its further variation will be practically immaterial and only slightly affect the resulting reaotance of the generator circuit. This condition corresponds to a new desired state of balance.

In accordance with the present invention in View of the above, the starting is effected in such a manner that when the generator is switched in by suitable means, the disturbin influence of the insufficient saturation 0 the apparatus, the iron of which is stronglysaturated during operation, will be eliminated.

This ma be accomplished, for example, by decreasing the value of the self inductance L upon the switching in of the generator below the normal value by an amount corresponding approximately to the excess of the beginning self inductance L of the apparatus d qver itsnormal working value.

By normal value of the inductive reactance of the apparatus d, is meant the value which it assumes when the installation is in operation.

. Furthermore, when the generator is switched in, it is advisable to increase the self induction L above its normalworking value and thereby to decrease its lagging current which has to neutralize only a small leading current, or none at all, in the branch z z It may be advisable also simultaneously to use both expedients, i. e. to start the assembly by-decreasing the inductance L When the full value of the current is obtained the mentioned values will be set to their normal operation value.

Finally, we may eliminate the insufficient saturation of the resultant disturbing increase of self induction L, of apparatus (1 in the following mannerfA direct current winding associated with the apparatus (Z is temporarily traversed by a direct current which decreases the magnetic permeability of the apparatus and therefore decreases its self induction. i Thisarrangement is illustrated in Fig. 4 1n which'e 'is'the direct current winding of the v apparatus d, b is a battery current source and h a circuit controlling key.

A very short direct current impulse is sufiicient for starting the apparatus. If the installation is so tuned that the full primary and secondary current is supplied when the apparatus d is without direct current, then i the currents will reach their full working value when the key It is opened. If the key small and will lie behind point P (Fig. 2). The direct current winding 6 and the key it may be used for starting as well as the sending of signals or telephonic messages.

It is not necessary that the key control the switching in and out of the full value of the direct current but the system may be so arranged in the well known manner that upon the actuation of the key the value of the direct current will vary between two limits.

If no directcurre'nt source is obtainable, then the starting winding 6 may be fed from a low frequency alternating current source Having described our invention, what we claim is: y

1. An arrangement for supplying a transformer requiring a large magnetizing current bydrawing only a small current from 20. the source of power comprising, a source of alternating voltage, a transformer requiring a high magnetizing current coupled to said source, variable tuning means comprising means in series with said'transformer for enabling saidtransformer under normal operation to take a current of the required value leading the voltageof said source and for enabling said transformer under starting conditions to take sufiicient current to decrease the re'actance of the transformer to the point beyond which its reaetance will decrease with increase in current, said tuning means also including an inductive reactance in parallel with said transformer and series tuning means, to correct the power factorin said source.

2. A method of starting frequency-trans forming installations having a frequency changer and tuning means including a normal inductive reaetance when the installation is in operation arranged in series with the generator and an inductance arranged in parallel. with the tuning means and the frequency changer, which consists in decreasing the inductive reaetance of the tuning means below normal by an amount corresponding approximately to the excess at the beginning oflthe operation of the install'ation of the inductive reaetance of the frequency changer above normal and then restoring the inductive reaetance of the tuning means to its normal value after the current in the generator circuit hasattained considerable strength.

3. A method 'of starting frequency-transforming installations having a frequency changer and tuning means including a nor mal inductive reaetance when the installation is in operation arranged in series with the generator and an inductance arranged in parallel with the tuning means and the frequency changer, which consists in decreasing the inductive reaetance of the tuning means to cause the current in the generator circuit to build up to considerable strength and then restoring the inductive reaetance of the tuning means to its normal value so as to tune the generator circuit of the installation to the basic frequency of the generator.

l. Method of starting frequency transforming installations having normal operating circuit constants comprising, adjusting the constants of the frequency transformer circuit so that suflicient current flows thru the said transformer to decrease its reactance to the point beyond which its reaetance will decrease with increase in current, and then adjusting the constants back to normal values.

5. A method of starting frequency-transforming installations having a frequency changer and tuning means including a normal inductive reaetance when the installation is in operation arranged in series with the generator and an inductance arranged in parallel with the tuning means and the frequency changer, which consists in de-. creasing the inductive reaetance of the tuning means in series with the frequency changer and increasing the variable inductance in parallel with the frequency changer to cause'the current in the generator circuit to build up to a predetermined strength and then restoring the above-mentioned inductances to their normal values.

6. A method for starting frequency transforming installations which consists of a source of voltage, a frequency transformer, tuning means for the said frequency transformer havin a normal operating reaetance and a power factor correcting device having a lagging power factor characteristic for said source under normal load comprising, increasing the capacity reaetance of the tuning means, decreasing the load taken by said device and then restoring the reaetance of said tuning means and the value of the load taken by said device to normal value.

In testimony whereof we afiix our signatures. 

